What is the d20 Modern SRD missing that the d20 Modern book has, aside from the usual (character creation, character advancement, "flavour")?

I'm intrigued by the Shadow Chasers setting, but from what little I've read of it, I have a rather different approach in mind. I'm wondering if, given that I've got the SRDs and the classic triumvirate (PHB/DMG/MM), I'd be missing anything important.